Currently, the number of people more than 55 years old comprises more than 10% of the total population of this country, and thus it is considered that the number of patients suffering from dementia will greatly increase with the inevitable increase of the number of old people in the population, whereby serious problems will arise due to the increase in the number of patients suffering from dementia, the burden on families having to attend to such patients, and the necessity for an increase in the number of medical institutions.
Accordingly, the development of brain function-improving medicines such as psychotropic drugs and dementia-curing agents is urgently required.
As a medicine for remedy of schizophrenia, namely a psychotropic drug, Haloperidol, Chlorpromazine and Tetrabenazine are used.
These medicines, however, have adverse side effects such as a reduction of the learning function, and thus the administration of these medicines is limited, and therefore, a satisfactory medicinal effect cannot be obtained thereby.